Predicting risk and outcomes for frail older adults:a protocol for an umbrella review of available frailty screening tools

The aim of this systematic review is to comprehensively search the available literature and to summarize the best available evidence from systematic reviews in relation to published screening tools to identify pre-frailty and frailty in older adults, that is: (i) to determine their psychometric proprieties; (ii) to assess their capacity to detect pre-frail and frail conditions against established methods; and (iii) to evaluate their predictive ability. More specifically, the review will focus on the following questions: Frailty is an age-related state of vulnerability resulting from a balance between the maintenance of health and the deficits threatening it.1,2 This clinical condition compromises the ability to cope with daily or acute stressors and, further, increases the risk of adverse outcomes, predisposing those involved to disability and dependency on others for daily life activities, and leading to hospitalization and institutional placement.3,4 It is also a predictor of higher mortality rates.4-7 In the absence of biological markers, an operational definition of frailty has been proposed.2,8 This definition is based on physical markers, including weakness with low muscle strength (e.g. poor grip strength), overall slowness (particularly of gait), decreased balance and mobility, fatigability or exhaustion, low physical activity and involuntary weight loss. For diagnostic purposes, at least three of these symptoms must be observed.8 The presence of only one or two of them indicates the earlier stage of frailty, namely, pre-frailty. Despite high predictive validity of this operational definition, and despite its common use in clinical settings, many researchers believe it is insufficient, asserting that it should also include cognitive and mental health domains, and possibly also social domains such as living alone.9-12 Other dimensions recognized as important for identifying frailty are the ability to deal with activities of daily living and quality of life, as for individuals with this clinical condition both of these areas tend to be decreased.9,13 This lack of consensus on the definition of frailty (based on physical markers as opposed to a broader multidimensional approach) is also reflected in divergences related to the prevalence data obtained from epidemiological studies. Systematic comparison of these data14 shows that frailty prevalence differs from 4% to 17% in the population aged 65 and over, and in case of pre-frailty, prevalence varies from 19% to 53% of the same age group, with average values of 10.7% and 41.6%, respectively. The divergences between estimates are also conditioned by demographic variables such as age and gender. Namely, for elders aged 80-84 the prevalence of frailty is estimated as 15.7%, and for elders over the age of 84, 26.1%. Additionally, women tend to have higher rates of frailty than men. Although the condition of frailty has been studied for years, there is no consensus on its pathophysiologic mechanism. According to some authors2,8,15, this state of increased vulnerability is due to accumulation of subthreshold decrements in physiologic reserves that affects multiple physiologic systems. Other authors16,17 have described frailty in terms of progressive dysregulation in a number of main physiologic systems and their complex interconnected network, and subsequent depletion of homeostatic reserve and resiliency. Recently, discussion on the psychopathological mechanism of this clinical condition has been enriched by new theoretical proposals associating frailty to reduced capacity to compensate ageing-related molecular and cellular damage.13,18 In all these approaches it is assumed that the development of frailty may be modulated by disease. In other words, it can be precipitated or exacerbated by the occurrence of comorbid pathological conditions.19-21 It is also suggested that increased vulnerability for adverse health outcomes can precede the onset of chronic diseases.19,20 However, according to Bergman et al19, it is probable that in this case, frailty is just a manifestation of subclinical and undiagnosed stages of such diseases. Because of the high prevalence and the severity of adverse outcomes of frailty, its screening should be a priority in appropriate components of primary care networks (including general practice, geriatrics, psychology, etc.), as well as in institutional or community care settings. Early diagnosis of this clinical condition can help improve care for older adults, making possible the minimization of the risk of pre-frail states developing into frail states (primary prevention), and implementation of therapeutic measures in order to attenuate or delay underlying conditions and symptoms, or to ameliorate the impact on independence or healthy and engaged lifestyles (loss of which would in turn have a further impact on frailty development, i.e. secondary prevention).2,4 In more advanced stages, frailty assessment provides valuable data necessary to plan and implement intervention strategies oriented to the preservation of functional status or to control the progression of adverse outcomes, such as recurrent hospitalizations, institutionalization or death (tertiary prevention).2,4 The evidence obtained from the implementation of various types of interventions for frailty indicates that the frailty condition can be managed and reduced.22-25 Screening for frailty can also provide information on populations at high risk of disability and poor prognosis, and help to identify reversible risk factors.2 These data are especially important for determining variables that make specific interventions more beneficial to specific patients. In order to identify individuals at risk of frailty, several assessment tools have been developed. The most widely cited focus on physical markers of frailty2,8 or are based on the accumulation of deficits from physical, cognitive, mental health and functional domains.13,26 However, both types of measures seem to be insufficient. The first one does not cover all dimensions of frailty and consequently does not provide indications useful to treatment choice and care planning, and the last one is time consuming and thus is difficult to integrate into day-to-day health care practice.27 In more recent approaches, the indices created for frailty assessment integrate demographic, medical, social and functional information, and demonstrate their usefulness either for diagnostic purposes or to predict adverse health outcomes.28 According to the literature, there are more than 20 different measures being used for frailty screening. Nonetheless, it is still unknown how their characteristics match different samples within the frail/pre-frail condition and robust populations, and what is the best fit between these measures, purposes (e.g. to predict need for care, mortality or potential response to intervention) and contexts/populations to assess frailty in older age. Also, the reliability and validity of these measures need to be clarified, as well as the comparative sensitivity and specificity in identifying patients at risk of a poor prognosis. A scoping search identified a large number of relevant systematic reviews; however in most cases they are confined to specific assessment measures related to a specific clinical model (phenotype model8, cumulative deficits model13 and predictive model28). For a clear view and objective evaluation of existing tools, this set of evidence needs to be systematized, compared and synthesized. In other words, it is essential to conduct an umbrella review. A preliminary search of the JBI Database of Systematic Reviews and Implementation Reports, the Cochrane Database of Systematic Reviews, Prospero, CINAHL and Medline has revealed that there is currently no overview of reviews or umbrella review (neither published nor in progress) on this topic of sufficient reliability, validity and capacity to detect pre-frail and frail conditions, and with predictive accuracy of available screening tools for frailty in older adults29 The main goal of this umbrella review is to consolidate the available evidence regarding screening for pre-frailty and frailty from the published literature. More specifically, reviews will be summarized in order to determine the quality of screening tools in terms of frailty diagnosis and frailty prognosis